general_fact: 1617 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 1617 is the maximum value of n so that there exist 6 denominations of stamps so that every postage from 1 to n can be paid for with at most 9 stamps.
trivia: 1617 is a boring number.
historical_date: June 4th is the day in 1989 that Ali Khamenei is elected the new Supreme Leader of Islamic republic of Iran by the Assembly of Experts after the death of Ayatollah Ruhollah Khomeini.